Electrical pasteurizing process



Nov. 30, 193 7.

B. E. GETCHELL ELECTRICAL PASTEURIZING PROCESS Filed June 1, 1936 2 Sheets-Sheet 1 INVENTOR BENJAMI ZKrTORNEY GETCHELL,

NOV. 30, 1937. B GETCHELL 2,100,328

ELECTRICAL PASTEURI Z ING PROCES 5 Filed June 1, 1936 2 Sheets-Sheet 2 INVENTOR BENJAMIN E. GETCHELL,

,A'TORNEY Patented Nov. 30, 1937 I UNITED STATES PATIENT OFFICE ELECTRICAL PASTEURIZING PROCESS Benjamin E. Getchell, Plainville, Conn., assignor to The Trumbull Electric Manufacturing Company, Plainville, Conn, a corporation of Con necticut Application June 1, 1936, Serial No. 82,700

6 Claims. (01. 219-20) My invention relates to a system or process for The circulating system consists of a pump 8, treating liquids and especially milk. Such treata conduit or pipe line 9, a preheater or regenment is customarily called pasteurization. The erative heat exchanger l0, an electrical heating present process involves the use of alternating chamber II, a holding chamber I2, a discharge current for raising milk to the pasteurizing temspray head or. spreader l3, and a collector l4 5 Deratllre. from which the treated milk may be fed to a One object of the invention is to maintain a bottling machine (not shown). steady flow of milk and control the temperature The pump is driven by an electric motor l5 by varying the power input to the heating chamand the rate of flow of the liquid is controlled her. This variation is accomplished by means by a manually operable valve IS in conduit 9. 10 of an auto transformer and relays automatically The temperature of the heated milk is indicated actuated by a temperature controlled contactor. by thermometer l'l arranged betwe the heating In commercial operation it is highly desirable chamber and the holdin c a d the that the output of the system be synchronized D a e f e milk as it leaves the holding with the demands or capacity of a bottling machamber is recorded by a suitable instrument I8. 15 chine and for this purpose I provide a manual After the milk passes over the heat regenerator control for the flow of milk. The milk is prefcoils l0, refrigerating coils l9 may be used to fure ably pumped through the system-by a pump ther cool the liquid before it reaches collector l4. through which the milk can flow backward to the A temperature controlled contactor or switch supply in case the pump stops. The pump is device 20 is actuated by suitable thermostatic driven preferably by an electric motor of a conelements including a sensitive element 2| which stant speed type, the starting and stopping of is located at the top of the heating chamber. which is controlled thermostatically from the Suitable mechanism -for this purpose will be milk or other liquid. Variations in the temperafound shown and described in my application ture of the raw milk supply, the electrical con- Serial Number 752,223, now Patent No. 2,052,396, ductivity of the milk, the temperature of the where I have also shown and described a suitroom and/or the line voltage are compensated able mechanism for cooling the electrodes of the for automatically by the variation in voltage heating chamber. from the auto-transformer. The system is preferably designed to be oper- 39 In the treatment of milk it is highly desirable ated from a standard commercial 110-220 volt that the temperature and time'of treatment be A. 0.3 wire system. This will ordinarily be conaccurately controlled within narrow limits. One trolled at the entrance by a main switch (not of my objects is to provide a practical, reliable shown). and efficient process for this purpose.

Another object is to provide a system which is General description of electrical circmts wholly automatic once it has been started and In the drawings the electrical circuits have which will automatically operate to compensate been shown diagrammatically. In each case, for variations in conditions which affect the temwhen the coils of the magnetic contactors or reperature of the treated liquid. In this conneclays are energized the movable elements move 40 tion it is essential that provision be made to predownward. When the coils are not energized, the 40 vent the passage of liquid through the system elements move upward. I unless it has been properly'treated. A manually operated switch 22 controls the Another object is to provide a system through pump l5. It also energizes the line side of which the flow can be manually set for one or switch 23. another predetermined speed of delivery as de- The control switch 23 is dependent upon switch 45 termined by the operator. 22 for its supply of energy. This switch 23 Fig. lis adiagrammatic view showing the liquid nishes the power to all of the control circuits. circulating system with the temperature 0011- and also to the alarm circuit.

trolled contactor and the temperature recording A temperature control contactor 20 is Op fio instrument. ated by means of bulb 2! in the milk flow, just Fig. 2 is a diagrammatic view showing the cirabove the heating chamber, and is responsive cuits of the electrical control. to variations in temperature of the milk. In 2| The liquid to be treated is supplied from on are three contacts, 25, which actuate the circuit or more reservoirs such as 5 and 6 with a selecguarding against milk flow below the minimum I tive valve 1. pasteurizing temperature, 26, to correct temperature if it drops degree or more below the pasteurizing point,- and 2?, tocorrect temperature if it rises degree or more above pasteurizing point.

Heating chamber i i has been mentioned above. It contains a pair of electrodes between which the milk flows and from which electric current is transmitted through the milk stream. The power input to this chamber is supplied by auotransformer 33 through magnetic contactors 35, 36, 3? and 33.

A water relay (it is in the circuit of the contactors furnishing power to the heating chamber. Failure of cooling water to flow over the electrodes of the heating chamber will cause this relay G3 to interrupt the supplyof power to the heating chamber.

A low milkrelay 62 is in the coil circuit of the alarm relay 26. If the milk in the raw milk tank drops below predetermined level, it will open the magnet circuit of this contactor, allowing the alarm circuit to go on and notify the operator. 1 The pump motor 63 is under manual control of switch 22 and under automatic control of re-= lay (it.

The low milk alarm 33 is under control of relays O2 and 23.

An auxiliary electrode 36 is inthe pump stop circuit. It is in the circuit of relay 35 and if milk is flowing by this electrode when 20 engages the contact 23, due to temperatures below the pasteurizing minimum, a circuit is completed through relay 63 which opens the pump motor circuit. If there is no conducting fluid such as milk or saline solution beyond the top of the heating chamber at tll the circuit through relay 433 will not be completed and the pump will not stop.

Magnetic contactor 35 furnishes volt power from auto-transformer 33' .to the heating chamber it. It is under the control of water relay cc and also relay 615.

A magnetic contactor 36 supplies 235 volt power from the auto-transformer to the heating chamber. It is under control of relay 33 and operates to increase power in case the temmrature drops deg ee or more below Dasteurizing temperature. This contactor is also under control of water relay 13.

A magnetic contactor 31 supplies 220 volt power from the auto-transformer to-the heating chamber. .This contactor is under control of water relay 33 and is normally closed when the temperature is within degree of the pasteurizing point. v

Magnetic contactor 33 supplies 205 volt power from the auto-transformer to the heating chamher i i. This contactor is under control of relay 5i and relay 6t and operates to decrease the power to the heating chamber, in case the temperature of the milk rises degree 01' more above the pasteurizing point. I

It should be noted that magnetic contactors 33, 33 and 33 all have auxiliary contacts which electrically interlock with relays d3, 33 and Si in such a manner that only one of these contactors can close at one and the same time. The closing of any one will automatically break the circuit of the other three, so that it will be impossible for two contactors to close at once, and thus short-circuit the windings of the autotransformer.

The auto-transformer 3G is connected across the 220 volt line, and has 110, 205, 220 and 235 volt taps. These taps do not necessarily have arouses to be exactly the voltage specified, but may be anything which will give the required power' to take care of the range desired for heating chamber ll.

Relay 35 is under control of the contact 23 of contactor 20 and also under control of electrode M. It controls the pump and the circuits of contactors 35, 36, 37 and 38. When this relay A5 is not energized it permits the pump to operate and will permit contactors 33, 37 and 33 to open and close according to their individual controls, but will not permit 35 to close. When relay a5 is energized, it opens the magnetic circuits of 36, 37 and 33 so that their controls are inefiective. Energizing this relay 65 also closes the magnetic circuit of contactor 35. This supplies the heating'chamber i I! with 110 volt power when the pump is not operating and the milk is flowing backward.

Relay 3% governs contactor 3t and is under the control of contact 23 of temperature controlled contactor 2D and operates when the temperature drops degree or more below pasteurizing point.

A relay 5| governs contactor 33. It is under control of contact/2i of temperature controlled contactor 2D and operates when the temperature rises degree or more above the pasteurizing point. Relays Q8 and 55 combined, govern contactor 37. If neither 53 nor 56 is energized by contactor 23, circuit is established through contactor 3'3, but if either 33 or 55 is energized by contactor 23, the magnetic circuit of contactor 3i is interrupted.

Relay 25 in the low milk alarm circuit is under control of low milk relay 42. It automatically notifies the operator in case the milk supply drops below a predetermined level,

The pump motor circuit Upon closing switch 22 a circuit is established through the right hand leg of relay 15 to the pump motor 85. Thus the pump is under manual control of switch 22 and under automatic control of relay 65.

Normal condition operating circuits Closing switch 22 completes a circuit as previously described through the pump motor 55. Closing switch 23 completes a circuit through the left side of relay 435 to the left side of relay 13 to the left side of relay 39 through the right hand auxiliary contact of contactor 33, auxiliary contact of contactor 38 through the magnet of contactor 3'1? to the auxiliary contact of contactor 35 and thence to water relay :33 to ground.

This energizes the coil of contactor 3?, which closes its'contacts and supplies 220 volt power Normal low temperature control In case the treating temperature drops V2 degree or more below the pasteurizing point, contactor 28, through contact 23, energizes the coil of relay 58 which acts to open the magnet circuit of contactor 37, thus removing 220 volts from electrodes. This circuit is opened at the left hand contact of relay 33. Relay 33 at the same time closes the circuit through the magnet of contactor 36. This circuit goes through the right hand leg of contactor 48 through the magnet of contactor 36, then to the auxiliary contact of contactor 31 and from there through the auxiliary contact of contactor 35 and from there through relay 40 to ground.

Thus it is seen that although relay 48 connects this circuit to the magnet of contactor 36, it cannot be completed until contactor 31 opens, and its auxiliary contact closes, and that magnetic contactor 35 must also be opened 50 that its auxiliary contact is closed.

Contactor 36 then closes, because its coil is energized, and the 235 volt circuit from auto-transformer to the heating chamber is made, thus raising the voltage so it will increase the temperature of the milk under treatment.

As soon as the temperature reaches within degree of the pasteurizing point, the coil of relay 4 48 will be de-energized by contactor 26 of contactor 20 and normal operation will be resumed as previously described under Normal condition operating circuits.

High temperature control In case the temperature rises degree or more above pasteurizing point, contactor 20 at contact 21 energizes the coil of relay 5! which operates and breaks the magnetic circuit of contactor 31 through the left hand leg of relay 5|. At the same time relay 5| establishes a circuit through its right hand leg to the magnet of contactor 38. From there it goes through the auxiliary contact of contactor 31, then through the auxiliary contact of contactor 35, and from there to relay 46, to ground.

Thus it will be seen that the main contacts of contactor 31 must be in open position so as to close its auxiliary contact before the magnet of contactor 38 can be energized.

Contactor 38, because its coil is energized, closes the 205 volt power circuit from the auto-transformer to the electrode chamber, thus lowering the voltage so as to reduce the temperature of the milk under treatment.

As soon as the temperature of the treated liquid, as measured by bulb 2|, reaches within degree of the pasteurizing point, contact 21 of contactor 20 opens the coil circuit of relay 5| and normal operation is resumed.

Abnormal low temperature control In case the pasteurizing temperature drops below the pasteurizing minimum, it is desired to stop the flow of milk through the apparatus. Just before this occurs, contactor 20 at contact 26 will have energized the coil of relay 48 which establishes the circuits as described under Normal low temperature control, with contactor supplying 235 volt power to the electrode chamber. Now contactor 20 will also close a circuit at contact 25 through the coil of relay 45, auxiliary electrode 44, through the milk stream, to ground.

As soon as the coil of relay 45 is energized, the pump motor circuit is interrupted and the forward flow of milk ceases. The left hand leg of relay 45 breaks the power supply circuit to the magnets of contactors 36 and 31 which causes their main contacts to open and their auxiliary contacts to close.

This left hand leg of relay 45 closes the circuit through the magnet of contactor 35 which then goes through the left hand auxiliary contact of contactor 36 and from there through relay 40 to ground. Thus it will be seen that contactor 36 must open so that its auxiliary contact will be closed,.before the magnet of contactor 35 can be energized.

Contactor 35 now closes and supplies 110 volt power to the heating chamber, treating the backward flow of milk, while the pump is stopped. This is done to avoid overheating of the backward flowing milk.

As soon as the milk has allreturned to the heating chamber for reheating, the coil circuit of relay is broken at auxiliary electrode 44 which permits the pump to start, and also causes 235 volt power to be re-supplied to the heating chamber.

If the temperature is now above the pasteurizing minimum, contactor 20 will open the circuit of relay 45 at contact 25 and permit the pump to continue in operation. If not, relay 45 will again stop the pump and return the milk for further treatment. This operation of starting and stopping will continue until the milk reaches the proper pasteurizing temperature, at which time normal operation will be resumed.

Electrode cooling water failure In case of failure of water flow for cooling the electrodes, it is desirable to shut oil the supply of power to the electrodes to prevent them from becoming overheated and burning the milk as it passes through. It will be noted that relay 40 controls the circuits of the magnets of contactors 35, 36, 31 and 38. Failure of water flow over the electrodes causes this relay 4!! to break these magnetic circuits. This causes all four cont-actors to remain in the open position, interrupting the power supply to heating chamber I I.

The treating temperature of the milk will immediately drop, causing the coil of relay 45 to become energized and interrupt the pump motor circuit.

The milk will return to the heating chamber and the pump will alternately start and stop, taking tests on the milk temperature as before, but no milk will be permitted to pass, as the temperature cannot come up to the pasteurizing point while the power is oil, and this testing will go on indefinitely until the water flow over the electrodes is re-established. The power circuits will then go on according to conditions as described above under low temperature controls, and as soon as the treating temperature reaches the proper point normal operation will again be resumed.

Low milk alarm circuit In case the raw milk supply drops below a predetermined level in the milk tank, relay 42 acts to open the magnetic circuit of relay 24. This allows the contacts of relay 24 to close and establishes a circuit through the alarm 43 which no-. tifies the operator that his raw milk supply will soon become exhausted so that he may either renew the supply or prepare to shut down the plant, as desired.

Starting operation is not stopped on flow temperatures below the minimum pasteurizing point.

Tank 5 is provided with milk and tank 6 is provided with saline solution. Valve 7! is turned to permit fluid from the saline solution tank to flow through the system. Valve i6 is set to approximately the flow desired. The electrode cooling water is turned on, and the waste water from the electrodes actuates the water relay 40 so that when control switch 23 is closed, circuit will be established through the magnetic contactors according to the position of contactor 26.

Switch 22 is now closed, which starts the pump motor i5 and supplies power to the line side of switch 25. Switch 23 is now-closed, which actuates the control circuits and causes 235 volt power to be supplied to heating chamber H due to the fact that contactor 28 is contacting at 26. This starts the sequence of operations described under "Normal low temperature control, resulting in the closing of contactor 36 to supply 235 volts for increasing the heating efi'ect in chamber |i'. Thus during the period of bringing the temperature of the saline solution from cold up to the set pasteurizing point, the highest voltage is applied to heating chamber ii.

The fluid passing through the heating chamber is gradually raised in temperature and is passed over the regenerative coils It. This results in raising the temperature of the fluid as it enters the heating chamber, and further raises the temperature of the fluid as it leaves the heating chamber. l

This increased heat, in turn, raises the regenerative temperature still further and the cycle continues until the temperature of the treated fluid reaches'the pasteurizing temperature as set at 20.

The contactor 28 may now be set at a desired working pasteurizing temperature, say 162 degrees. This will cause contact 26 toopen the coil circuit of relay 418 and establish normal operating conditions.

Almost immediately contact 2? will be closed, due to the new lower setting, and the operation described under High temperature contro will take place, resulting in the decrease of power to the heating chamber. The pasteurizing temperature willlthen drop rapidly until it reaches within one-half degree of 162 degrees, for which id-is set. At this time, contact -27 will open the coil circuit of relay 5! and normal operation will start. The temperature of the treated fluid will now stabilize at 162 degrees and any variation one-ha1f degree above or below that point willcause proper operation of the auto-transformer to correct the temperatureto the set point.

Valve l isnow thrown over so as to cause the milk to flow from tank 5 and follow the saline solution through the system, thus driving all of the water out of .the system and establishing a steady flow of milk. As soon as this is accomplished, the milk is led to the bottling machine from collector Ml. If the speed, of flow does not synchronize with the bottling r'nachine speed, it may be increased or decreased by manual operation of valve i6 and the controls will act to mainta n the temperature of the pasteurized milk at the proper point automatically, regardless of any change that may be made within reasonable limits.

The process of shutting down the plant is the reverse of starting, and is accomplished simply by throwing the valve l in position to supply saline solution to the pump. This solution follo'ws the milk through the plant, driving it all out,

at whichtime the controls may be thrown ofi and the plant shut down.

The second method of starting is accomplished by starting directly with the raw milk. In this method valve 1? is thrown into position to feed raw' milk into the system. Electrode cooling water is turned on, .as before, temperature controller .20 is set at the desired pasteurizing temperature, switch 22 is closed, starting the pump, and switch 23 is immediately closed, which will put into operation the control system. The pump will operate until the milk reaches electrode 66. The temperature of this first flow of milk will be far below the pasteurizing temperature due to the fact that regeneration of heat in the coils W has not yet been established. Therefore 2&9 will contact at 25 and at 26. Operation of the controls will follow as described under Abnormal low temperature control, the pump starting and stopping, and tests being made by bulb 25, until the milk reaches the proper temperature, at which time it will be permitted to leave the heating chamber.

This milk will again be followed by milk below the minimum pasteurizing point because of the fact that regeneration has not yet been estab lished, and this second lot of milk will be retained in the electrode chamber until it reaches the proper pasteurizing point, as previously described.

This operation will continue until finally enough milk has been permitted to pass to bring the regenerative temperature up sufliciently high to permit continuous operation. The plant will then go into normal operation until all of the milk has been pasteurized. L

The process of shutting down is practically the same as in the first method except that fresh water may be used to drive the milk out of the system.

I claim:

1. A pasteurizing apparatus including an electrio heater having aconduit with a heating chamber having spaced electrodes, means for applying alternating currentjo said electrodes, means for passing a liquid through said heater, means for inductively changing the voltage supply to said electrodes, and means responsive to the temperature of the liquid which has passed through the heater for controlling said voltage changing means, said last mentioned means including a selective contactor for increasing the voltage on the electrodes when the temperature of the liquid falls a small amount below a predetermined value and another selective contactor for decreasing the voltage on the electrodes when the temperature of the liquid rises a small amount above said predetermined value,-said voltage changing means including an auto-transformer having taps for voltages a small amount above and below that of line voltage and also a tap for applying a voltage substantially below line voltage tosaid electrodes.

2. A pasteurizing apparatus including an electric heater having a conduit with a heating chamber having spaced electrodes, means for applying alternating current to said electrodes, means for passing a liquid through said heater, means for inductively changing the voltage supply to said electrodes, and means responsive to the temperature of the liquid which has passed through the heater for 5 controlling said voltage, changing means, said last mentioned means including a selective contactor for increasing the voltage on the electrodes when the temperature of the liquid falls a small amount below a predetermined value and another selective contactor for decreasing the voltage on the electrodes when the temperature of the liquid rises a small amount above said predetermined value, and a third selective contactor for greatly reducing the voltage on the electrodes when the temperature of the liquid falls below another predetermined value lower than any of said aforementioned values.

3. A pasteurizing apparatus including an electric heater having a conduit with a heating chamber having spaced electrodes, means for applying alternating current to said electrodes, means for passing liquid through the heater, means for stopping the liquid and back-flowing itthrough the heater when the temperature of the liquid falls below a predetermined minimum value, means for inductively reducing the voltage applied to said electrodes alarge amount during said backflow, and means for automatically actuating said means for passing liquid through'the heater upon completion of said backflow.

4. A pasteurizing apparatus including an elec tric heater having a conduit with a heating chamber having spaced electrodes, means for applying alternating current to said electrodes, means for passing liquid through the heater, means for stopping the liquid and backflowing it throughthe heater when the temperature of the liquid ,falls below a predetermined -minimum value, means for inductively reducing the voltage applied to said electrodes a large amount during said backflow, and means for automatically actuating said means for passing liquid through the heater upon completion of said backfiow, said last mentioned means having a mechanism for inductively increasing the voltage on said electrodes above line voltage on reactuating said means for passing liquid through the heater.

5. A pasteurizing apparatus including an electric heater having a conduit with a heating chamber having spaced electrodes, means for applying alternating current to said electrodes, means for passing liquid through the heater, a contactor for regulating line voltage to the electrodes, mechanism for selectively supplying more or less than line voltage to the electrodes, a selective contactor responsive to a decrease in the temperature of the liquid which has passed through the heater for increasing the voltage on the electrodes above that of line voltage, and another selective contactor responsive to an increase in temperature of the liquid which has passed through the heater for decreasing the voltage applied to the electrodes to an amount less than that of line voltage.

6. A pasteurizing apparatus including an electric heater having a conduit with a heating chamber having spaced electrodes, means for applying alternating current to said electrodes, means for passing liquid through the heater,

a contactor for regulating line voltage to the electrodes, mechanism for selectively supplying more or less than line voltage to the electrodes, a selective contactor responsive to a decrease in the temperature of the liquid whichhas passed through the heater for increasing the voltage on the electrodes above that of line voltage, another selective contactor responsive to an increase in temperature of the liquid which has passed through the heater for decreasing the voltage applied to the electrodes to an amount less than that of line voltage, and a third. selective contactor for greatly reducing the voltage applied to the electrodes in response to a reduction in temperature of the liquid more than a predetermined minimum value, which is less than that for eflecting an increase in voltage on the electrodes.

' BENJAMIN E. GETCHELL. 

